Balance bike



FIG. 1 is a front elevation view of a balance bike showing my new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a left side elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a top, front and right side perspective view thereof.

The broken lines in the drawings illustrate portions of the balance bike which form no part of the claimed design. 

CLAIM The ornamental design for a balance bike, as shown and described. 